SFI SYSTEM, Diagnostic DTC:P2120, P2122, P2123, P2125, P2127, P2128, P2138

DTC Code	DTC Name
P2120	Throttle / Pedal Position Sensor / Switch "D" Circuit
P2122	Throttle / Pedal Position Sensor / Switch "D" Circuit Low Input
P2123	Throttle / Pedal Position Sensor / Switch "D" Circuit High Input
P2125	Throttle / Pedal Position Sensor / Switch "E" Circuit
P2127	Throttle / Pedal Position Sensor / Switch "E" Circuit Low Input
P2128	Throttle / Pedal Position Sensor / Switch "E" Circuit High Input
P2138	Throttle / Pedal Position Sensor / Switch "D" / "E" Voltage Correlation

DESCRIPTION

This ETCS (Electronic Throttle Control System) does not use a throttle cable.

The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type, and uses Hall-effect elements, in order to yield accurate signals, even in extreme driving conditions, such as at high speeds as well as very low speeds. The voltage, which is applied to terminals VPA and VPA2 of the ECM, varies between 0.5 V and 4.75 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal opening angle (throttle valve opening angle) and is used for engine control. A signal from VPA2 conveys the status of the VPA circuit and is used to check the APP sensor itself.

The ECM monitors the actual accelerator pedal opening angle (throttle valve opening angle) through the signals from VPA and VPA2, and controls the throttle actuator according to these signals.

DTC No.	DTC Detection Condition	Trouble Area
P2120	VPA fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)	Accelerator Pedal Position (APP) sensor ECM
P2122	VPA 0.4 V or less for 0.5 seconds or more when accelerator pedal fully released (1 trip detection logic)	APP sensor Open in VCP1 circuit Open or ground short in VPA circuit ECM
P2123	VPA 4.8 V or more for 2.0 seconds or more (1 trip detection logic)	APP sensor Open in EPA circuit ECM
P2125	VPA2 fluctuates rapidly beyond upper and lower malfunction thresholds for 0.5 seconds or more (1 trip detection logic)	APP sensor ECM
P2127	VPA2 1.2 V or less for 0.5 seconds or more when accelerator pedal fully released (1 trip detection logic)	APP sensor Open in VCP2 circuit Open or ground short in VPA2 circuit ECM
P2128	Conditions (a) and (b) continue for 2.0 seconds or more (1 trip detection logic): (a) VPA2 4.8 V or more (b) VPA between 0.4 V and 3.45 V	APP sensor Open in EPA2 circuit ECM
P2138	Condition (a) or (b) continues for 2.0 seconds or more (1 trip detection logic): (a) Difference between VPA and VPA2 0.02 V or less (b) VPA 0.4 V or less and VPA2 1.2 V or less	Short between VPA and VPA2 circuits APP sensor ECM

Tech Tips

When any of these DTCs are set, check the APP sensor voltage by entering the following menus: Powertrain / Engine / Data List / ETCS / Accelerator Sensor Out No.1 and Accelerator Sensor Out No.2.

Trouble Area	Accelerator Sensor Out No.1 When Accelerator Pedal Released	Accelerator Sensor Out No.2 When Accelerator Pedal Released	Accelerator Sensor Out No.1 When Accelerator Pedal Depressed	Accelerator Sensor Out No.2 When Accelerator Pedal Depressed
VCP circuit open	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V
Open or ground short in VPA circuit	0 to 0.2 V	1.2 to 2.0 V	0 to 0.2 V	3.4 to 4.75 V
Open or ground short in VPA2 circuit	0.5 to 1.1 V	0 to 0.2 V	2.6 to 4.5 V	0 to 0.2 V
EPA circuit open	4.5 to 4.98 V	4.5 to 4.98 V	4.5 to 4.98 V	4.5 to 4.98 V
Normal condition	0.5 to 1.1 V	1.2 to 2.0 V	2.6 to 4.5 V	3.4 to 4.75 V

Tech Tips

Accelerator pedal positions are expressed as voltages.

MONITOR DESCRIPTION

When either of the output voltages of VPA or VPA2 deviates from the standard range, or the difference between the output voltages of the 2 sensor circuits is less than the threshold, the ECM determines that there is a malfunction in the APP sensor. The ECM then illuminates the MIL and sets a DTC.

Example:

When the output voltage of VPA drops below 0.4 V for more than 0.5 seconds when the accelerator pedal is fully depressed, DTC P2122 is set.

If the malfunction is not repaired successfully, a DTC is set 2 seconds after the engine is next started.

FAIL-SAFE

When DTC P2120, P2121, P2122, P2123, P2125, P2127, P2128 or P2138 is set, the ECM enters fail-safe mode. If either of the 2 sensor circuits malfunctions, the ECM uses the remaining circuit to calculate the accelerator pedal position to allow the vehicle to continue driving. If both of the circuits malfunction, the ECM regards the accelerator pedal as being released. As a result, the throttle valve is closed and the engine idles.

Fail-safe mode continues until a pass condition is detected, and the engine switch is then turned off.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

These DTCs relate to the Accelerator Pedal Position (APP) sensor.

PROCEDURE

READ VALUE USING INTELLIGENT TESTER (ACCELERATOR POSITION)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Enter the following menus: Powertrain / Engine / Data List / ETCS / Accelerator Sensor Out No.1 and Accelerator Sensor Out No.2.

Read the value displayed on the tester.

Standard voltage

Accelerator Pedal Operation	Accelerator Sensor Out No.1	Accelerator Sensor Out No.2
Released	0.5 to 1.1 V	1.2 to 2.0 V
Depressed	2.6 to 4.5 V	3.4 to 4.75 V

CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS) Click here

CHECK HARNESS AND CONNECTOR (ACCELERATOR PEDAL POSITION SENSOR - ECM)

Disconnect the A36 Accelerator Pedal Position (APP) sensor connector.
Disconnect the A14 ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard resistance (Check for open)

Tester Connection	Condition	Specified Condition
A36-6 (VPA) - A14-29 (VPA)	Always	Below 1 Ω
A36-5 (EPA) - A14-20 (EPA)	Always	Below 1 Ω
A36-4 (VCPA) - A14-23 (VCPA)	Always	Below 1 Ω
A36-3 (VPA2) - A14-28 (VPA2)	Always	Below 1 Ω
A36-2 (EPA2) - A14-21 (EPA2)	Always	Below 1 Ω
A36-1 (VCP2) - A14-22 (VCP2)	Always	Below 1 Ω

Standard resistance (Check for short)

Tester Connection	Condition	Specified Condition
A36-6 (VPA) or A14-29 (VPA) - Body ground	Always	10 kΩ or higher
A36-5 (EPA) or A14-20 (EPA) - Body ground	Always	10 kΩ or higher
A36-4 (VCPA) or A14-23 (VCPA) - Body ground	Always	10 kΩ or higher
A36-3 (VPA2) or A14-28 (VPA2) - Body ground	Always	10 kΩ or higher
A36-2 (EPA2) or A14-21 (EPA2) - Body ground	Always	10 kΩ or higher
A36-1 (VCP2) or A14-22 (VCP2) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

INSPECT ECM (VCPA AND VCP2 VOLTAGE)

Disconnect the A36 APP sensor connector.
Turn the engine switch on (IG).

Measure the voltage according to the value(s) in the table below.

Standard voltage

Tester Connection	Switch Condition	Specified Condition
A14-23 (VCPA) - A14-20 (EPA)	Engine switch on (IG)	4.5 to 5.5 V
A14-22 (VCP2) - A14-21 (EPA2)	Engine switch on (IG)	4.5 to 5.5 V

REPLACE ECM Click here

REPLACE ACCELERATOR PEDAL ROD ASSEMBLY
1. Replace the accelerator pedal rod assembly Click here.
NEXT

CHECK WHETHER DTC OUTPUT RECURS (ACCELERATOR PEDAL POSITION SENSOR DTCS)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Clear DTCs Click here.
Start the engine.
Fully depress and release the accelerator pedal.
Enter the following menus: Powertrain / Engine / DTC.

Read the DTCs.

Result

Display (DTC Output)	Proceed to
P2120, P2122, P2123, P2125, P2127, P2128, and/or P2138	A
No output	B

SYSTEM OK

REPLACE ECM Click here